1. Field of the Invention
The present invention generally relates to secure password or passcode entry systems and, more particularly, to a new method of password or passcode entry which is very secure from password or passcode detection by casual observation of key hits during entry.
2. Background Description
One of the most popularly used and simple methods for providing access to computer systems, secure areas, financial transaction systems and others is by password entry through a keyboard or keypad. A visual display unit is often associated with such systems. For example, a standard method for password entry routinely used for various access control situations is the entry of an alphanumeric password through a standard ASCII (American Standard Code for Information Interchange) keyboard or a numeric keypad. The user""s key entry is not revealed on the screen directly, but an asterisk xe2x80x9c*xe2x80x9d or some such character is displayed in response to each entry of a character.
In many of these systems, it is possible for an unauthorized observer to note the sequence of key entries and make a quick guess of the valid password. While frequent change of password by the authorized person can prevent this possibility to some extent, an unauthorized person can still exploit the access to the systems before the password is changed. Also, in electronic banking (e-banking) systems such as automatic teller machines (ATMs), the user""s password or passcode cannot usually be changed frequently. Therefore, it is highly desirable that any password or passcode entry system be secure against disclosure to observers. Further, such systems must also be immune to observation of keyboard or keypad entry and the visual display units by using secretly installed video cameras. Unauthorized persons can analyze video recordings at leisure and make out the password or passcode possibly with the help of a computer program. To date several proposals exist to address this problem, but they are generally open to disclosure through video camera recordings, even though they make it very difficult for casual observers to detect the password or passcode.
For example, U.S. Pat. No. 5,428,349 to Baker proposes a non-disclosing password entry system. Here, the password entry method is effected by displaying pseudo-random two-dimensional array of characters. The user is required to enter the row (or column) number in which the user""s password character appears. For entry of each character, a different array of characters is displayed to the user. Thus, this method does not directly reveal the password characters, but only reveals a set of characters among which a valid character exists. In the Baker method, with 26 alpha characters and 10 numeric characters, a 6xc3x976 character array is displayed, and each entry indicates 6 characters. While this method is claimed to be relatively secure from password detection by an unaided onlooker, a video recording of display and keyboard and later analysis can lead to password detection with some effort. This method has a drawback that for each character entry, the user has to visually inspect the 6xc3x976 pseudo-random character array and identify the valid character. This can be quite tedious and time consuming for an average user. Also, another drawback of this method is that for any given password, there can be several others which map to the same set of rows (or columns), and this makes it less secure from random password guessing.
U.S. Pat. No. 5,276,314 to Martino et al. proposes an identity verification system wherein a two-dimensional array of characters or symbols is displayed to the user. Keys are provided here to effect certain transformations of the array elements. For example, pressing a xe2x80x9crowxe2x80x9d key can circularly shift the characters in that row by one position to the left. By such transforming steps, the user is required to bring the characters of his or her password in certain known positions in the array. From a practical point of view, a 4xc3x974 or 5xc3x975 array is the maximum array size that may be acceptable for manipulation by an average user. The method is quite secure from a casual onlooker but is still susceptible to code detection through video recordings. Also, the user is required to identify his or her password characters and successively manipulate the entries. This amounts to solving some sort of puzzle and, therefore, the method is generally not acceptable for use by an average user.
It should be noted that in password entry methods such as discussed above, it is generally difficult to prevent videographing of the keyboard by covering the keyboard because the user needs to see the keys that he or she is going to press. Considering the limitations of the aforementioned methods, it is clear that there is a need for a new method for password or passcode entry which is secure from detection even with the aid of a video recording system.
It is therefore an object of the present invention to provide a new method of password or passcode entry that is very secure from password detection by either casual observation or video recording of key hits during password or passcode entry.
According to the invention, password entry is done by displaying to a user distinct codes corresponding to characters in the user""s password. The user then serially enters codes corresponding to characters while concealing the entry. Only a limited number of keys are used for password entry. In one example, two keys, a xe2x80x9cHITxe2x80x9d key and a xe2x80x9cNEXTxe2x80x9d key, are provided within a concealing hood, and the password in entered serially as a number of xe2x80x9cHITxe2x80x9d key hits. The user is prompted to enter digits corresponding to symbols of his or her password with a display of unique m-ary number codes assigned mutually exclusively to different characters. The scheme can be easily implemented in existing computer systems entirely through a conventional ASCII keyboard or mouse, by using adjacent keys on the keyboard or left and right mouse buttons. As the method requires only a few keys, concealing the keys to prevent viewing of key entry is possible.